백준 26069 c++

//set으로 다시 한번 풀어보기

#include <iostream>
#include <vector>
#include <string>
#include <map>
#include <algorithm>

using namespace std;

int input(int lower, int upper);
void input_names(vector <pair<string, string>>& name, int size);
int dance_count(vector <pair<string, string>> name);

int main(void)
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);

	int N;
	vector <pair<string, string>> name;

	N = input(1, 1000);
	input_names(name, N);
	cout << dance_count(name) << "\n";

	return 0;
}

int input(int lower, int upper)
{
	//cout << "input()" << endl;
	int A;

	while (1)
	{
		cin >> A;
		if (A >= lower && A <= upper)
		{
			break;
		}
		else
		{
			;
		}
	}

	return A;
}

void input_names(vector <pair<string, string>> &name, int size)
{
	//cout << "input_names()" << endl;
	int i;
	string temp1, temp2;

	for (i = 0; i < size; i++)
	{
		cin >> temp1 >> temp2;
		if (temp1.length() <= 20 && temp2.length() <= 20 && temp1 != temp2)
		{
			name.push_back(make_pair(temp1, temp2));
		}
		else
		{
			i--;
		}
	}

	return;
}
int dance_count(vector <pair<string, string>> name)
{
	//cout << "dance_count()" << endl;
	int count = 1, i;
	int size = name.size();
	map <string, bool> dance_list;//중복 비허용
	string first, second;

	dance_list.emplace("ChongChong", true);
	for (i = 0; i < size; i++)
	{
		first = name[i].first;
		second = name[i].second;
		if (dance_list.find(first) == dance_list.end() && dance_list.find(second) == dance_list.end())//ChongChong을 만난 사람과 만나지 못한 경우
		{
			;
		}
		else//ChongChong또는 ChongChong과 만난 사람과 만난 경우//중복 비허용
		{
			dance_list.emplace(first, true);
			dance_list.emplace(second, true);
		}
	}
	count = dance_list.size();

	return count;
}